In July 2015, Russian internet entrepreneur Yuri Milner that he would be giving $100 million to the 'Breakthrough Listen' initiative - the biggest hunt for aliens that the world has ever seen.
The project begun on the Green Bank Telescope in West Virginia, and at Lick Observatory in California, but now they've been joined by the Parkes Radio Telescope in New South Wales, Australia.
“The addition of Parkes is an important milestone,” Milner. “These major instruments are the ears of planet Earth, and now they are listening for signs of other civilizations.”
After 14 days of commissioning and test observations, the hunt began on 7 November with observations of Proxima b - a newly-discovered Earth-sized planet orbiting Proxima Centauri. The planet is known to be in the habitable zone of its red dwarf star, which is about 4.3 light years from Earth, meaning that it's possible that there is liquid water on the surface.
“The chances of any particular planet hosting intelligent life-forms are probably minuscule,” said Andrew Siemion, director of UC Berkeley SETI Research Center.
“But once we knew there was a planet right next door, we had to ask the question, and it was a fitting first observation for Parkes. To find a civilization just 4.2 light years away would change everything.”
That's just the start, however. The Parkes observations will cover all 43 stars within five parsecs of Earth, listening at frequencies between one and 15 gigahertz, as well as 1000 stars within 50 parsecs at 1-4GHz and a million others at the same frequencies for just a minute each.
After that, it will scan the galactic plane and center, the centers of 100 other nearby galaxies, and a bunch of other, more exotic sources - like white dwarfs, neutron stars, and black holes - all at at 1-4GHz.
All the data gathered will be freely available to the public online, and the Breakthrough Institute has invited scientists, programmers, students, and anyone else interested to help sift through the observations and see if there's anything interesting in them. If that sounds a bit much, you can just install the , allowing your computer to comb through the data itself in idle moments.
"The Parkes Radio Telescope is a superb instrument, with a rich history," said Pete Worden, Chairman of Breakthrough Prize Foundation and Executive Director of the Breakthrough Initiatives. "We’re very pleased to be collaborating with CSIRO to take Listen to the next level."

It’s a bold claim. Two astronomers think they have spotted messages from not just one extraterrestrial civilisation, but 234 of them. The news has sparked a lively debate in the field as other astronomers think the claim is premature and are working fast to get to the bottom of the signals.
In 2012, Ermanno Borra at Laval University in Quebec suggested that an extraterrestrial civilisation might use a laser as a means of interstellar communication. If the little green men simply flashed a laser toward the Earth like a strobe light, we would see periodic bursts of light hidden in the spectrum of their host star. They would be incredibly faint and rapid, but a mathematical analysis could uncover them.
“The kind of energy needed to generate this signal is not crazy,” says Borra. In fact, Borra showed that technology we have on Earth today – specifically the Helios laser at the Lawrence Livermore National Laboratory – could generate that kind of signal, should we want to reveal ourselves to the cosmos.
With this in mind, Borra’s graduate student Eric Trottier combed through 2.5 million stars recorded by the Sloan Digital Sky Survey in search of such a signal. He found it, down to the exact shape, in 234 stars.
The overwhelming majority of those stars are in the same spectral class as the sun, which Borra says supports his hypothesis that this signature must be the result of extraterrestrial intelligent life. And with the data in hand, he thinks that 234 distinct civilisations are beaming pulses of the same periodicity (roughly 1.65 picoseconds) toward the Earth.
Borra and Trottier ruled out other possible explanations for the pattern, like rapid pulsations in the atmospheres of the stars themselves and rotational transitions in molecules. “We have to follow a scientific approach, not an emotional one,” says Borra. “But intuitively – my emotion speaks now – I strongly suspect that it’s an ETI signal.”
Other astronomers think that Borra’s intuition might have run away with him.
“They don’t consider every natural possibility and jump prematurely to the supernatural – so to speak – conclusion,” says Peter Plavchan at Missouri State University in Springfield. “I think it’s way too premature to do that.”
“There is perhaps no bolder claim that one could make in observational astrophysics than the discovery of intelligent life beyond the Earth,” says Andrew Siemion, the director of the SETI Research Centre at the University of California Berkeley. “It’s an incredibly profound subject—and of course that’s why many of us devote our lives to the field and put so much energy into trying to answer these questions. But you can’t make such definitive statements about detections unless you’ve exhausted every possible means of follow-up.”
So that’s exactly what the Breakthrough Listen Initiative—a project headed by Siemion that searches for signs of intelligent life beyond Earth—will do. The team plans to observe several stars from Borra’s sample with the 2.4-meter Automated Planet Finder telescope at the Lick Observatory in California.
Borra is excited to see that others are taking the reins. “At this stage, the signal is so strange, that although our detailed analysis seems to indicate that it is a real signal, it has to be validated with more work,” he says.
Still, the Breakthrough Listen team doesn’t share Borra’s enthusiasm. According to a statement, they have rated the detection as a zero to 1 on the Rio Scale for SETI observations, meaning that it is insignificant.
In fact, Siemion thinks the spectral patterns were likely caused by errors in calibration or data analysis. And Plavchan agrees. He points to several steps in the team’s data analysis that “scared him” because they didn’t consider how those steps might affect their results—a red flag in any scientific claim. At the end of the day, the signal probably comes down to a human error, he says.
“It’s not a bad idea to look for a signal, it’s just that they didn’t do their homework,” says Plavchan.

Here are some of the highlights of the year that was.
The spectacular announcement that ripples in the very fabric of spacetime itself had been found (and from surprisingly massive black holes colliding) sent similarly massive ripples through the scientific community. The discovery was made using the Laser Interferometer Gravitational-Wave Observatory (LIGO) and represents a fundamentally new sense with which to see the universe.
The gravitational waves cause one arm of the LIGO detector to stretch relative to the other by less than a thousandth of the width of a proton in the centre of the atom. Relatively speaking, that's like measuring a hair's-width change in the distance to the nearest star.
This discovery was the end of a century-long quest to prove Einstein's final prediction that these gravitational waves are real. It also allows us to directly "see" that famously and fundamentally invisible entity: the black hole (as well as definitively proving its existence). The fact that the two black holes collided 1.3 billion years ago and the waves swept through Earth just days after turning the detector on only add to the incredible story of this discovery.
The year started so well for SpaceX with the incredible achievement of sending a satellite into orbit, which is no mean feat itself at such low cost, before then landing that launch rocket on a barge in the ocean. A seemingly unstoppable sequence of launches and landings made it appear that a new era of vastly cheaper access to space through rockets that could be refuelled and reused was at hand.
Unfortunately, with the explosion of a Falcon 9 on the launchpad, the company was grounded, but apparently hopes for a resumed launch in early January.
Add to that the visionary plans to settle Mars outlined by Elon Musk, albeit not without some audacious challenges, and it's been a year of highs and lows for SpaceX.
Proxima Centauri is our Sun's nearest neighbour at just over four light years away, and it appears that its solar system may contain an Earth-like world. Until this year, astronomers weren't even sure that any planets orbited the star, let alone ones that might harbour the best extrasolar candidate for life that spacecraft could visit within our lifetime.
The planet, creatively named "Proxima b", was discovered by a team of astronomers at Queen Mary University in London. Using the light of Proxima Centuari, the astronomers were able to detect subtle shifts in the star's orbit (seen as a "wobble"), which is the telltale sign that another massive object is nearby.
While Proxima Centuari is barely 10% the size of our Sun, Proxima b's orbit is only 11 days long, meaning it is very close to the star and lies just within the so-called habitable zone. However, follow-up with either Hubble or the upcoming James Webb Space telescope is necessary to determine if the exoplanet is as well suited for life as Earth.
With a potential Earth twin identified in Proxima b, now the challenge is to reach it within a human lifetime. With the breakthrough initiative starshot, which has been funded by Russian billionaire Yuri Milner and endorsed by none other than Stephen Hawking, lightweight nanosails can be propelled by light beams to reach speeds up to millions of kilometres an hour.
Such speeds would allow a spacecraft to arrive at Proxima b in about 20 years, thus enabling humans to send information to another known planet for the first time.
However, there are many challenges ahead, such as the fact that the technology doesn't exist yet, and that high-speed collisions with gas and dust between stars may destroy it before it can reach its target.
But humans have proven to be resourceful, and key technology is advancing at an exponential rate. Incredibly the idea of sailing to another world is no longer science fiction, but rather an outrageously ambitious science project.
Perhaps, aliens are already sending out their own information in the form of radio transmissions. In another breakthrough initiative called Listen, also championed by Hawking, astronomers will be searching the habitable zones around the million closest stars to try to detect incoming radio transmissions. Involving Australia's very own Parkes telescope (as well as the Green Bank Telescope and Lick Observatory at visible wavelengths of light), observations have been running through 2016 and the search for alien signals will continue for the next decade.
In 2014 the Philae lander became the first space probe to land on a comet, and even though its crash landing dictated that its science transmission would be a one-off, its recent rediscovery by Rosetta has allowed it to continue to contribute to analysis of comet 67P.
Philae's crash location, as well as the orientation of the doomed probe, has allowed astronomers to accurately interpret data taken by Rosetta regarding the composition of the comet.
While Philae has literally been living under (crashed on) a rock for the past two years, Rosetta has been the busy bee, taking numerous images, spectroscopy and other data of the comet.
In fact, data taken from Rosetta's spectrometer has been analysed and revealed that the amino acid, glycine, is present in the comet's outgassing, which breaks away from the surface of the comet as it becomes unstable from solar heating. Glycine is one of the fundamental building blocks of life; necessary for proteins and DNA, and its confirmed extraterrestrial confirms that the ingredients for life are unique to Earth, and that we may have comets to thank for providing our microbial ancestors with those crucial ingredients.
Outlook for Down Under
The future for astrophysics in Australia in 2017 looks particularly bright, with two ARC Centres of Excellence: CAASTRO-3-D studying the build of atoms over cosmic time; and OzGRav exploring the universe with gravitational waves; as well as SABRE, the world's first dark matter detector in the Southern Hemisphere, installed by end of the year.
If you thought 2016 was a great year in space, then you're in for a treat in 2017.
Dust and gas emitted from comet 67P reveal an amino acid. Credit: ESA
Explore further: LIGO discovery named Science's 2016 Breakthrough of the Year

The National Astronomical Observatories of China (NAOC) is joining forces with the Breakthrough Initiatives to launch a coordinated search for evidence of intelligent life beyond Earth
Using some of the world's most powerful telescopes. NAOC's brand-new FAST telescope - the world's largest filled-aperture radio receiver - will join the Breakthrough Listen program at Green Bank Telescope in the US and the Parkes Observatory in Australia, and together the organization's will exchange observing plans, search methods and data - including the rapid sharing of promising new signals for additional observation and analysis. The two parties are also planning a series of meetings and conferences to refine search strategies, data analyses and results.
At a signing ceremony at NAOC headquarters in Beijing, the collaboration was announced via a joint statement by Prof. Jun Yan, Director General of NAOC, and Pete Worden, Chairman of Breakthrough Prize Foundation and Executive Director of Breakthrough Initiatives. They looked forward to "a long and productive scientific collaboration," and invited scientists around the world to join in "one of humanity's greatest quests."
"'Are we alone?' is a question that unites us as a planet," said Yuri Milner, Founder of the Breakthrough Initiatives, "And the quest to answer it should take place at a planetary level too. With this agreement, we are now searching for cosmic companions with three of the world's biggest telescopes across three continents."
"The Five-hundred-meter Aperture Spherical Telescope (FAST), located in Guizhou, China, achieved first light in September 2016. It is the world's largest filled-aperture radio receiver, and will be one of the most powerful instruments to search for the potential intelligent life beyond Earth," said Prof. Jun Yan, the Director General of NAOC. "We are delighted to be collaborating with the Breakthrough Initiatives."
"The FAST telescope is a remarkable instrument with unprecedented power," said Pete Worden, Executive Director of the Breakthrough Initiatives. "We are delighted to be collaborating with NAOC."
The Breakthrough Initiatives are a set of long-term astronomical programs exploring the Universe, seeking scientific evidence of life beyond Earth, and encouraging public debate from a planetary perspective. Breakthrough Listen, launched in July 2015, is the most comprehensive astronomical search for intelligent life ever undertaken. It employs two of the world's biggest radio telescopes: the Green Bank Telescope in West Virginia, USA, and the Parkes Observatory in New South Wales, Australia; as well as the Automated Planet Finder at Lick Observatory in California, USA, which searches for laser signals.
- Martin Rees, Astronomer Royal, Fellow of Trinity College; Emeritus Professor of Cosmology and Astrophysics, University of Cambridge.
- Pete Worden, Chairman, Breakthrough Prize Foundation.
- Frank Drake, Chairman Emeritus, SETI Institute; Professor Emeritus of Astronomy and Astrophysics, University of California, Santa Cruz; Founding Director, National Astronomy and Ionosphere Center; Former Goldwin Smith Professor of Astronomy, Cornell University.
- Dan Werthimer, Co-founder and chief scientist of the SETI@home project; director of SERENDIP; principal investigator for CASPER.
- Andrew Siemion, Director, Berkeley SETI Research Center.
For media inquiries: media@breakthroughprize.org
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Parkes joins the Green Bank Telescope (GBT) in West Virginia, USA, and the Automated Planet Finder (APF) at Lick Observatory in California, USA, in their ongoing surveys to determine whether civilizations elsewhere have developed technologies similar to our own. Parkes radio telescope is part of the Australia Telescope National Facility, owned and managed by Australia's Commonwealth Scientific and Industrial Research Organization (CSIRO).
Drawing on over nine months of experience in operation of the dedicated Breakthrough Listen instrument at GBT, a team of scientists and engineers from the University of California, Berkeley's SETI Research Center (BSRC) deployed similar hardware at Parkes, bringing Breakthrough Listen's unprecedented search tools to a wide range of sky inaccessible from the GBT. The Southern Hemisphere sky is rich with targets, including the center of our own Milky Way galaxy, large swaths of the galactic plane, and numerous other galaxies in the nearby Universe.
'The Dish' at Parkes played an iconic role in receiving the first deliberate transmissions from the surface of another world, as the astronauts of Apollo 11 set foot on our Moon. Now, Parkes joins once again in expanding human horizons as we search for the answer to one of our oldest questions: Are we alone?
"The Parkes Radio Telescope is a superb instrument, with a rich history," said Pete Worden, Chairman of Breakthrough Prize Foundation and Executive Director of the Breakthrough Initiatives. "We're very pleased to be collaborating with CSIRO to take Listen to the next level."
With its new combined all-sky range, superb telescope sensitivity and computing capacity, Breakthrough Listen is the most powerful, comprehensive, and intensive scientific search ever undertaken for signs of intelligent life beyond Earth.
Moreover, this expansion of Breakthrough Listen's range follows the announcement on October 12 that it will be joining forces with the new FAST telescope – the world's largest filled-aperture radio receiver – to coordinate their searches for artificial signals. The two programs will exchange observing plans, search methods and data, including the rapid sharing of promising new signals for additional observation and analysis. The partnership represents a major step toward establishing a fully connected, global search for intelligent life in the Universe.
"The addition of Parkes is an important milestone," said Yuri Milner, founder of the Breakthrough Initiatives, which include Breakthrough Listen. "These major instruments are the ears of planet Earth, and now they are listening for signs of other civilizations."
After 14 days of commissioning and test observations, first light for Breakthrough Listen at Parkes was achieved on November 7, with an observation of the newly-discovered Earth-size planet orbiting the nearest star to the Sun. Proxima Centauri, a red dwarf star 4.3 light years from Earth, is now known to have a planet ("Proxima b") within its habitable zone – the region where water could exist in liquid form on the planet's surface. Such "exo-Earths" (habitable zone exoplanets) are among the primary targets for Breakthrough Listen.
"The chances of any particular planet hosting intelligent life-forms are probably minuscule," said Andrew Siemion, director of UC Berkeley SETI Research Center. "But once we knew there was a planet right next door, we had to ask the question, and it was a fitting first observation for Parkes. To find a civilization just 4.2 light years away would change everything."
As the closest known exoplanet, Proxima b is also the current primary target for Breakthrough Listen's sister initiative, Breakthrough Starshot, which is developing the technology to send gram-scale spacecraft to the nearest stars.
"Parkes is one of the most highly cited radio telescopes in the world, with a long list of achievements to its credit, including the discovery of the first 'fast radio burst'. Parkes' unique view of the southern sky, and cutting-edge instrumentation, means we have a great opportunity to contribute to the search for extra-terrestrial life," said Douglas Bock, Director of CSIRO Astronomy and Space Science.
As with the other Breakthrough Listen telescopes, data from Parkes will be freely available to the public online. Scientists, programmers, students, and others are invited to access the Breakthrough Listen archive for scientific research purposes, including helping perfect algorithms to sift through petabytes of raw data from the telescopes, screening for interfering signals from earth-bound technology. Volunteers can also help analyze data from Parkes by donating their spare computing power as part of BSRC's legendary SETI@home project.
Breakthrough Listen at Parkes will be the most comprehensive search of the southern sky for artificial signals in six key samples:
Explore further: Breakthrough Listen to search for intelligent life around weird star

Twenty years ago this month, Geoffrey Marcy narrowly missed out on becoming the first astronomer to find a planet orbiting a distant star. Beaten to the discovery by a pair of Swiss scientists, Marcy and his colleagues went on to rack up an astonishing list of other extrasolar planet sightings, from the first multiplanet system around a Sun-like star to the first Neptune-sized exoplanet. It was the kind of career that triggered talk of a Nobel prize.
On 14 October, Marcy resigned from the University of California, Berkeley, in the wake of a sexual-harassment scandal that involved multiple students over many years. He leaves a field that has expanded far beyond his early influence — and many researchers who hope that the harassment revelations will lead to improvements in working conditions for women in astronomy.
Having such a prominent researcher involved in a high-profile harassment case may prompt more scientists to recognize the deep-seated problem, says Julianne Dalcanton, an astronomer at the University of Washington in Seattle. “Perhaps moving forward, more people will be part of the solution,” she says. Already, astronomy departments at many universities are starting to hold open discussions about how to prevent abuses on their campuses.
“The damage he has caused and the culture which enabled it to happen still need to be addressed,” adds Laura Lopez, an astronomer at the Ohio State University in Columbus.
Statistics paint a grim picture for US women in astronomy. Just 14% of full professors in the field at US universities are women, according to a 2013 survey by the American Astronomical Society (AAS) Committee on the Status of Women in Astronomy. Studies suggest that sexual harassment is pervasive in academia. In an April 2015 survey of students, faculty members, staff and alumni in Marcy’s department at Berkeley, more than one-third of 45 women reported some form of sexual or gendered discomfort brought on by the actions of other members of the department.
Prompted by formal complaints, Berkeley investigated Marcy and concluded in June that he had violated campus sexual-harassment policies in incidents involving students between 2001 and 2010. (Marcy became a professor at the university in 1999.) The revelations became public in a 9 October article on BuzzFeed News. Berkeley administrators said that because they could not unilaterally discipline a faculty member, they had reached an agreement with Marcy in which he would be stripped of faculty career protections and be subject to sanctions or dismissal if he violated policies again.
Astronomy faculty members and students at Berkeley protested against the university’s response, and Marcy resigned. San Francisco State University, where he worked before Berkeley and had retained an adjunct position, terminated its relationship with him.
The fate of Marcy’s research projects remains unclear. That includes his work helping to lead NASA’s planet-hunting Kepler mission, and with the Automated Planet Finder, a robotic 2.4-metre telescope at Lick Observatory in northern California that searches for rocky planets. Marcy has resigned as a principal investigator of Breakthrough Listen, a US$100-million project announced in July to accelerate the search for signs of intelligent life in the Universe. The mission will continue to be overseen by Berkeley astronomers Andrew Siemion and Dan Werthimer, among others.
Although Marcy was a pioneer in exoplanet research, the field has grown far beyond him, says Mercedes López-Morales, an astronomer at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts. She hopes that the quick and nearly universal condemnation of Marcy’s actions will encourage young researchers, particularly women, to pursue exoplanet research. “Marcy represents the exception, not the rule, in our field,” says López-Morales.
Among those swift responses was a statement from the AAS. The Marcy case “offers an important opportunity for all of us to discuss, within our groups and institutions, what responsibilities we have as professionals and how we can ensure that everyone in our profession is afforded a safe, supportive workplace”, it reads. AAS president Meg Urry, an astronomer at Yale University in New Haven, Connecticut, is a long-time advocate for improving working conditions for women. After the Marcy revelations, Urry set up a task force to develop procedures and sanctions related to misconduct, for inclusion in the society’s code of ethics.
“We should all take a close look at our own institutions and professional networks and ask what we might do differently,” says Heather Knutson, an exoplanet researcher at the California Institute of Technology in Pasadena.
Compared with other fields of science and other countries, US astronomy has been relatively progressive in tackling workplace issues for women and other minorities. The AAS Committee on the Status of Women in Astronomy runs a website with discussion and specific advice on topics such as bullying. Volunteers have also started a programme called Astronomy Allies, which serves as a buddy system to walk people home from astronomy-related parties and conference events.
Other research areas should also pay attention, Lopez says. “Sexual harassment is a problem endemic to all fields in academia,” she says, “and Marcy’s case should serve as a reality check for everyone, not just for astronomers.”

The blue-white dot at the center of this image is supernova 2012cg, seen by the 1.2-meter telescope at Fred Lawrence Whipple Observatory. At 50 million light-years away, this supernova is so distant that its host galaxy, the edge-on spiral NGC 4424, appears here as only an extended smear of purple light. Credit: Peter Challis/Harvard-Smithsonian CfA A team of astronomers including Harvard's Robert Kirshner and Peter Challis has detected a flash of light from the companion to an exploding star. This is the first time astronomers have witnessed the impact of an exploding star on its neighbor. It provides the best evidence on the type of binary star system that leads to Type Ia supernovae. This study reveals the circumstances for the violent death of some white dwarf stars and provides deeper understanding for their use as tools to trace the history of the expansion of the universe. These types of stellar explosions enabled the discovery of dark energy, the universe's accelerating expansion that is one of the top problems in science today.
The subject of how Type Ia supernovae arise has long been a topic of debate among astronomers.
"We think that Type Ia supernovae come from exploding white dwarfs with a binary companion," said Howie Marion of The University of Texas at Austin (UT Austin), the study's lead author. "The theory goes back 50 years or so, but there hasn't been any concrete evidence for a companion star before now."
Astronomers have battled over competing ideas, debating whether the companion was a normal star or another white dwarf.
"This is the first time a normal Type Ia has been associated with a binary companion star," said team member and professor of astronomy J. Craig Wheeler (UT Austin). "This is a big deal."
The binary star progenitor theory for Type Ia supernovae starts with a burnt-out star called a white dwarf. Mass must be added to that white dwarf to trigger its explosion - mass that the dwarf pulls off of a companion star. When the influx of mass reaches the point that the dwarf is hot enough and dense enough to ignite the carbon and oxygen in its interior, a thermonuclear reaction starts that causes the dwarf to explode as a Type Ia supernova.
For a long time, the leading theory was that the companion was an old red giant star that swelled up and lost matter to the dwarf, but recent observations have virtually ruled out that notion. No red giant is seen. The new work presents evidence that the star providing the mass is still burning hydrogen at its center, that is, that this companion star is still in the prime of life.
According to team member Robert P. Kirshner of the Harvard-Smithsonian Center for Astrophysics, "If a white dwarf explodes next to an ordinary star, you ought to see a pulse of blue light that results from heating that companion. That's what theorists predicted and that's what we saw.
"Supernova 2012cg is the smoking—actually glowing—gun: some Type Ia supernovae come from white dwarfs doing a do-si-do with ordinary stars."
Located 50 million light-years away in the constellation Virgo, Supernova 2012cg was discovered on May 17, 2012 by the Lick Observatory Supernova Search. Marion's team began studying it the next day with the telescopes of the Harvard-Smithsonian Center for Astrophysics.
"It's important to get very early observations," Marion said, "because the interaction with the companion occurs very soon after the explosion."
The team continued to observe the supernova's brightening for several weeks using many different telescopes, including the 1.2-meter telescope at Fred Lawrence Whipple Observatory and its KeplerCam instrument, the Swift gamma-ray space telescope, the Hobby-Eberly Telescope at McDonald Observatory, and about half a dozen others.
"This is a global enterprise," Wheeler said. Team members hail from about a dozen U.S. universities, as well as institutions in Chile, Hungary, Denmark, and Japan.
What the team found was evidence in the characteristics of the light from the supernova that indicated it could be caused by a binary companion. Specifically, they found an excess of blue light coming from the explosion. This excess matches with the widely accepted models created by U.C. Berkeley astronomer Dan Kasen for what astronomers expect to see when a star explodes in a binary system.
"The supernova is blowing up next to a companion star, and the explosion impacts the companion star," Wheeler explained. "The side of that companion star that's hit gets hot and bright. The excess blue light is coming from the side of the companion star that gets heated up."
Combined with the models, the observations indicate that the binary companion star has a minimum mass of six suns.
"This is an interpretation that is consistent with the data," said team member Jeffrey Silverman, stressing that it is not concrete proof of the exact size of the companion, like would come from a photograph of the binary star system. Silverman is a postdoctoral researcher at UT Austin.
Only a few other Type Ia supernovae have been observed as early as this one, Marion said, but they have not shown an excess of blue light. More examples are needed.
"We need to study a hundred events like this and then we'll be able to know what the statistics are," Wheeler said.
The work is published today in The Astrophysical Journal.
More information: "SN 2012cg: Evidence for Interaction Between a Normal Type Ia Supernova and a Non-Degenerate Binary Companion," G. H. Marion et al., 2016, Astrophysical Journal, Preprint: arxiv.org/abs/1507.07261

Breakthrough Listen, which was created last year with $100 million in funding over 10 years from the Breakthrough Prize Foundation and its founder, internet investor Yuri Milner, won't be the first to search for intelligent life around this star.
"The Breakthrough Listen program has the most powerful SETI equipment on the planet, and access to the largest telescopes on the planet," said Andrew Siemion, director of the Berkeley SETI Research Center and co-director of Breakthrough Listen. "We can look at it with greater sensitivity and for a wider range of signal types than any other experiment in the world. "
"Everyone, every SETI program telescope, I mean every astronomer that has any kind of telescope in any wavelength that can see Tabby's star has looked at it," he said. "It's been looked at with Hubble, it's been looked at with Keck, it's been looked at in the infrared and radio and high energy, and every possible thing you can imagine, including a whole range of SETI experiments. Nothing has been found."
While Siemion and his colleagues are skeptical that the star's unique behavior is a sign of an advanced civilization, they can't not take a look. They've teamed up with UC Berkeley visiting astronomer Jason Wright and Tabetha Boyajian, the assistant professor of physics and astronomy at Louisiana State University for whom the star is named, to observe the star with state-of-the-art instruments the Breakthrough Listen team recently mounted on the 100-meter telescope. Wright is at the Center for Exoplanets and Habitable Worlds at Pennsylvania State University.
The observations are scheduled for eight hours per night for three nights over the next two months, starting Wednesday evening, Oct. 26. Siemion, Wright and Boyajian are traveling to the Green Bank Observatory in rural West Virginia to start the observations, and expect to gather around 1 petabyte of data over hundreds of millions of individual radio channels.
"The Green Bank Telescope is the largest fully steerable radio telescope on the planet, and it's the largest, most sensitive telescope that's capable of looking at Tabby's star given its position in the sky," Siemion said. "We've deployed a fantastic new SETI instrument that connects to that telescope, that can look at many gigahertz of bandwidth simultaneously and many, many billions of different radio channels all at the same time so we can explore the radio spectrum very, very quickly."
The results of their observations will not be known for more than a month, because of the data analysis required to pick out patterns in the radio emissions.
First reported in September 2015 by Boyajian, then a postdoc at Yale University, Tabby's star - more properly called KIC 8462852 - had been flagged by citizen scientists because of its unusual pattern of dimming. These volunteers were looking at stars as part of the internet project Planet Hunters, which allows the public to search for planets around other stars in data taken by NASA's Kepler spacecraft, which has been monitoring 150,000 stars for regular dimming that might indicate a planet had passed in front of it.
But while most such dimming by transiting planets is brief, regular and blocks just 1 or 2 percent of the light of the star, Tabby's star dims for days at a time, by as much as 22 percent, and at irregular intervals.
While Boyajian speculated in her 2015 paper that the irregular dimming might be explained by a swarm of comets breaking up as it approached the star, subsequent observations show the star, which is located about 1,500 light-years from Earth in the constellation Cygnus, is far more irregular than a comet swarm would produce. In fact, it seems to have been dimming at a steady rate for the past century.
Speculation eventually arose that the dimming was caused by a Dyson structure: a massive orbiting array of solar collectors that physicist Freeman Dyson once proposed would be a natural thing for a civilization to build as it needed more and more energy to power itself. Theoretically, such a structure could completely surround the star - what he termed a Dyson sphere - and capture nearly all the star's energy.
How likely is that?
"I don't think it's very likely - a one in a billion chance or something like that - but nevertheless, we're going to check it out," said Dan Werthimer, chief scientist at Berkeley SETI. "But I think that ET, if it's ever discovered, it might be something like that. It'll be some bizarre thing that somebody finds by accident ... that nobody expected, and then we look more carefully and we say, 'Hey, that's a civilization.'"
Breakthrough Listen is monitoring many other stars using three telescopes that can peer into all segments of the cosmos: the Parkes Telescope in Australia and the Green Bank Telescope to search for radio transmissions, and the Automated Planet Finder at Lick Observatory in California to search for optical laser transmissions.
Follow the Berkeley SETI Research Center and Breakthrough Listen via social media: @BerkeleySETI on Twitter, as well as Facebook, Instagram, and YouTube.
Wright, Boyajian and Siemion will engage in a live video chat from the Green Bank Telescope at 4 p.m. EDT (1 p.m. PDT) Wednesday, Oct. 26, about their Tabby's star observations.

"The Breakthrough Listen program has the most powerful SETI equipment on the planet, and access to the largest telescopes on the planet," said Andrew Siemion, director of the Berkeley SETI Research Center and co-director of Breakthrough Listen. "We can look at it with greater sensitivity and for a wider range of signal types than any other experiment in the world. "
Breakthrough Listen, which was created last year with $100 million in funding over 10 years from the Breakthrough Prize Foundation and its founder, internet investor Yuri Milner, won't be the first to search for intelligent life around this star.
"Everyone, every SETI program telescope, I mean every astronomer that has any kind of telescope in any wavelength that can see Tabby's star has looked at it," he said. "It's been looked at with Hubble, it's been looked at with Keck, it's been looked at in the infrared and radio and high energy, and every possible thing you can imagine, including a whole range of SETI experiments. Nothing has been found."
While Siemion and his colleagues are skeptical that the star's unique behavior is a sign of an advanced civilization, they can't not take a look. They've teamed up with UC Berkeley visiting astronomer Jason Wright and Tabetha Boyajian, the assistant professor of physics and astronomy at Louisiana State University for whom the star is named, to observe the star with state-of-the-art instruments the Breakthrough Listen team recently mounted on the 100-meter telescope. Wright is at the Center for Exoplanets and Habitable Worlds at Pennsylvania State University.
The observations are scheduled for eight hours per night for three nights over the next two months, starting Wednesday evening, Oct. 26. Siemion, Wright and Boyajian are traveling to the Green Bank Observatory in rural West Virginia to start the observations, and expect to gather around 1 petabyte of data over hundreds of millions of individual radio channels.
"The Green Bank Telescope is the largest fully steerable radio telescope on the planet, and it's the largest, most sensitive telescope that's capable of looking at Tabby's star given its position in the sky," Siemion said. "We've deployed a fantastic new SETI instrument that connects to that telescope, that can look at many gigahertz of bandwidth simultaneously and many, many billions of different radio channels all at the same time so we can explore the radio spectrum very, very quickly."
The results of their observations will not be known for more than a month, because of the data analysis required to pick out patterns in the radio emissions.
First reported in September 2015 by Boyajian, then a postdoc at Yale University, Tabby's star – more properly called KIC 8462852 – had been flagged by citizen scientists because of its unusual pattern of dimming. These volunteers were looking at stars as part of the internet project Planet Hunters, which allows the public to search for planets around other stars in data taken by NASA's Kepler spacecraft, which has been monitoring 150,000 stars for regular dimming that might indicate a planet had passed in front of it.
But while most such dimming by transiting planets is brief, regular and blocks just 1 or 2 percent of the light of the star, Tabby's star dims for days at a time, by as much as 22 percent, and at irregular intervals.
While Boyajian speculated in her 2015 paper that the irregular dimming might be explained by a swarm of comets breaking up as it approached the star, subsequent observations show the star, which is located about 1,500 light-years from Earth in the constellation Cygnus, is far more irregular than a comet swarm would produce. In fact, it seems to have been dimming at a steady rate for the past century.
Speculation eventually arose that the dimming was caused by a Dyson structure: a massive orbiting array of solar collectors that physicist Freeman Dyson once proposed would be a natural thing for a civilization to build as it needed more and more energy to power itself. Theoretically, such a structure could completely surround the star – what he termed a Dyson sphere – and capture nearly all the star's energy.
How likely is that? "I don't think it's very likely – a one in a billion chance or something like that – but nevertheless, we're going to check it out," said Dan Werthimer, chief scientist at Berkeley SETI. "But I think that ET, if it's ever discovered, it might be something like that. It'll be some bizarre thing that somebody finds by accident … that nobody expected, and then we look more carefully and we say, 'Hey, that's a civilization.'"
Breakthrough Listen is monitoring many other stars using three telescopes that can peer into all segments of the cosmos: the Parkes Telescope in Australia and the Green Bank Telescope to search for radio transmissions, and the Automated Planet Finder at Lick Observatory in California to search for optical laser transmissions.
Explore further: Latest study of Tabby's star offers more weirdness

We’ve received a birth announcement from 20 million light years away, in the form of our first ever glimpse of what seems to be the birth of a black hole.
When massive stars run out of fuel, they die in a huge explosion, shooting out high-speed jets of matter and radiation. What’s left behind collapses into a black hole, which is so dense and has such strong gravity that not even light can escape it.
Or so the theory goes, anyway. Now, a team led by Christopher Kochanek at Ohio State University in Columbus have glimpsed something very special in data from the Hubble Space Telescope, from when it was watching the red supergiant star N6946-BH1, which is about 20 million light years from Earth.
This star, first observed in 2004, was once about 25 times the mass of our sun. Kochanek and his colleagues found that for some months in 2009, the star briefly flared a million times brighter than our sun, then steadily faded away. New Hubble images show that it has disappeared in visible wavelengths, but a fainter source in the same spot is detectable in the infrared, as a warm afterglow.
These observations mesh with what theory predicts should happen when a star that size crumples into a black hole. First, the star spews out so many neutrinos that it loses mass. With less mass, the star lacks enough gravity to hold on to a cloud of hydrogen ions loosely bound around it. As this cloud of ions floats away, it cools off, allowing the detached electrons to reattach to the hydrogen. This causes a year-long bright flare – when it fades, only the black hole remains.
There are two other potential explanations for the star’s disappearing act: it could have merged with another star, or be hidden by dust. But they don’t fit the data: a merger would shine more brightly than the original star for much longer than a few months, and dust wouldn’t hide it for so long.
“It’s an exciting result and long anticipated,” says Stan Woosley at Lick Observatory in California.
“This may be the first direct clue to how the collapse of a star can lead to the formation of a black hole,” says Avi Loeb at Harvard University.
The find needs further confirmation, but that may not be far off. Material falling into the black hole would emit X-rays in a particular spectrum, which could be spotted by the Chandra X-ray Observatory. Kochanek says his group will be getting new data from Chandra in the next two months or so.
If Chandra sees nothing, that doesn’t mean it’s not a black hole. In any case, the team will continue to look with Hubble – the longer the star is not there, the more likely that it’s a black hole. “Patience proves it no matter what,” says Kochanek.
This data will help describe the beginning of the life cycle of a black hole, and will inform simulations of how black holes form and what makes a massive star form a neutron star rather than a black hole.
Despite calling himself a “nasty pessimist”, Kochanek thinks it’s quite likely this is indeed the formation of a black hole. “I’m not quite at ‘I’d bet my life on it’ yet,” he says, “but I’m willing to go for your life.”